Because fewer than 50% of elderly depressed patients achieve remission and recovery in response to first-line antidepressant pharmacotherapy, the majority of patients are left with significant residual symptoms and functional impairment, putting them at risk of chronic, relapsing illness, non-adherence to other medical treatment, suicide, and family care giver burden. Our recently completed PROSPECT study has demonstrated the efficacy of collaborative depression care management in primary care settings for bringing about greater reductions in depressive symptoms and suicidal ideation in elderly with major depression, relative to usual care. Nonetheless, PROSPECT's intervention left a considerable burden of residual depressive symptoms, suggesting the need for further efficacy research to bring more patients to full remission and recovery. PROSPECT's intervention involved primarily collaborative clinical management and SSRI pharmacotherapy, with only 37% of patients also receiving a psychosocial treatment (Interpersonal Psychotherapy: IPT). We propose in this study to extend PROSPECT's model of collaborative care management to encompass more intensive treatment, hypothesizing that combined treatment with antidepressant medication (venlafaxine/clinical management) and psychosocial treatment (Interpersonal Psychotherapy) will be superior to venlafaxine/clinical management without IPT in bringing partial responders to symptomatic remission, reducing disabilities, and mitigating family caregiving burden. Working in five primary care practices, we will recruit and treat 320 patients with major depression aged 70 and older, using clinical management with venlafaxine (VENLA/CM, up to 150 mg/d for the first six weeks). Patients who are partial responders to VENLA/CM (n=160) will be randomly assigned to 10 weeks of extension therapy with either VENLA/CM (up to 300 mg/d) or VENLA/CM (up to 300 mg/d) and Interpersonal Psychotherapy (IPT, 10 sessions) (80 patients per cell). Randomization will be stratified by the presence/level of suicidal ideation and by level of cognitive impairment. We will model time to response and remission in the two randomized extension treatments via survival analysis. Changes over time in measures of depressive symptoms, hopelessness, suicidal ideation, disability, and family caregiving burden will be assessed in random regression models. This is the first controlled study of extended treatment of partially responding depression in old age. it will answer the question of how best to treat partial responders-by simply extending pharmacotherapy at higher doses, or by also adding psychotherapy-to remission and recovery. This is an amended (A2) competing continuation of (MH37869-21).